1. Field of the Invention
The present invention relates to a semi-conductor device, more specifically a semiconductor device having an air-tightly sealed package containing a circuit element therein and a waveguide connected with the package, in which the semiconductor device has a waveguide-coaxial line transformation structure.
2. Description of the Related Art
FIGS. 1 and 2 show perspective and sectional views of a conventional semiconductor device having an air-tightly sealed package containing a high frequency range circuit, e.g., an oscillator or an amplifier, which operates at a microwave range, and a waveguide attached to the package. FIGS. 1 and 2 are perspective and sectional views of the package. In these figures, 1 denotes a body or base of the package, 2 a cap of the package, 3 a waveguide-coaxial line transforming high frequency input terminal, 4 a terminal for a power source, 5 a terminal for internal control, 6 an IF (intermediate frequency) output terminal, 7 a semi-conductor circuit, and 8 a waveguide. In such a semiconductor device, the semiconductor circuit 7 is mounted on the base 1 of the package, the cap 2 is air-tightly (hermetically) sealed to the base 1 for protecting the semiconductor circuit 7, and the package is then attached to the waveguide 8.
To attach terminals 3 to 6 to the base 1, ready-made hermetically-glass-sealed terminals 3 to 6 are bonded to bore portions of the base 1 with a solder 9, a conductive resin, or the like. In FIGS. 5 and 6, 1' denotes a metal terminal, 2' a metal ring and 3' a glass dielectric spacer. Ready-made hermetically glass-sealed-terminals are used because, particularly for a waveguide-coaxial line transforming terminal, the shape of the terminal, the material and shape of the glass, etc., are severely limited when microwave impedance matching, prevention of radiation at the waveguide-coaxial converting part, etc., are considered. Also, because a glass-metal matching method is used, the materials of the metal members are limited from the viewpoints of heat resistance and bonding strength to glass. As a result, a terminal which fulfills the above requirements or conditions and can be easily attached to a base or body of a package is required.
The formation of terminals using a ready-made hermetically- glass-sealed terminal has, however, the following problems:
(1) The formation of bores of a base at which a hermetically sealed terminal is to be attached requires cutting or other complicated machining due to the complicated shape of the bores made necessary because the hermetically sealed terminal must be air-tightly fixed to the base. PA1 (2) In order to attach the hermetically sealed terminal, the thickness of a base of a package must be thick. PA1 (3) With regard to the above item (2), a simple method such as punching can not be used to bore a hole in a base of a package. PA1 (4) To maintain an air tight state between a hermetically sealed terminal and a base of a package, each terminal must be processed, for example, rotated, to ensure the bonding of the terminal to the base. This makes the batch process difficult. Also, this may sometimes result in a climb-up (creepage) of a solder from the interstice between a terminal and a base, causing a short circuit.